<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>hello vue!</title>
  <script src="https://unpkg.com/vue@3.4.21/dist/vue.global.js"></script>
  <style>

  </style>
</head>

<body>
  <div id="root"></div>
</body>
<script>
  const app = Vue.createApp({
    setup(props, context) {
      const msgRef = Vue.ref('helloworld')

      setTimeout(() => {
        msgRef.value = 'aaa'
      }, 1000)
      return {
        msgRef
      }
    }
  })
  const vm = app.mount('#root');
</script>

</html>